Because of the importance of the putting game to a golfer's overall score, there have been, and always will be, efforts to design a superior putter. A superior putter design should incorporate subjective characteristics such as feel and playability, as well as objective characteristics such as performance. Golf manufacturers will typically rely upon player testing and feedback in order to achieve optimum feel and playability in the putter, while relying upon quantitative measurements to confirm actual improvements in performance.
It is commonly understood and accepted by golfers that when putting a golf ball, the golf ball will roll more accurately and consistently if the initial backspin or skidding of the golf ball is minimized or eliminated, since backspin or skidding can cause the golf ball to travel in an unpredictable manner. Once the golf ball stops spinning backwards and/or skidding, and begins to roll in a forward direction, the golf ball will follow a more predictable path.
By designing putters with a lower center of gravity, manufacturers have been able to create putters that are more likely to impart a forward spin component to a putted golf ball. This can be explained by what is known as a vertical gear effect. The term gear effect is commonly used and understood in the industry. As a brief explanation of this effect, one can visualize a side view of a golf ball on the left hand side of a reference frame being impacted by a putter head coming from the right hand side of the reference frame. The impact point on the putter face is above the center of gravity of the putter head. Since the center of gravity is below the impact point, the torque forces will cause the putter head to rotate generally about the impact point in a clockwise direction, as viewed in the above-described reference frame, due to the location of the center of gravity. (Likewise, if the center of gravity were positioned above the impact point, the torque forces would cause the putter head to rotate generally about the impact point in a counterclockwise direction, as viewed in the above-described reference frame.) With the putter head rotating in a clockwise direction while the golf ball is in contact with the putter face, the putter face and golf ball will counter-rotate relative to one another, similar to two adjacent gears in a machine. Therefore, since the clockwise rotation of the putter head results in a clockwise rotation of the putter face, a counter-rotation on the golf ball will result in a counterclockwise rotation of the golf ball. Based upon the orientation of the reference frame described above, this counterclockwise rotation of the golf ball would be viewed as a forward rotation component.
As manufacturers have attempted to design putter heads having a lower center of gravity in order to achieve the desired vertical gear effect, manufacturers realized that limiting the putter head to a single material either made it difficult to get the center of gravity low enough, or to achieve a desirably proportioned putter head. Accordingly, manufacturers began utilizing materials of differing densities in order to design putter heads having a lower center of gravity, while retaining traditional proportions in a putter head design.
In an effort to design a superior putter, the inventors in the present application attempted to provide superior subjective characteristics by incorporating the commercially successful Stronomic.RTM. polymer insert into the putter face, while utilizing materials of differing densities in order to create a low center of gravity putter head that would produce the desirable vertical gear effect upon impact with a golf ball.
However, when such a design was player tested for feel and playability, a common complaint from the players was that the putter had a harsh or unpleasant feel. Efforts to determine the cause of this subjective characteristic have resulted in the present invention.